JPH05217904A - Separating method for element of semiconductor laser diode - Google Patents

Abstract

PURPOSE:To provide a method for separating many semiconductor laser diodes to be manufactured in a wafer state without forming a step instead of an etching method since various problems occur in the next step due to an overhang step to be formed on the side of an element when a separation groove for separating the diodes into independent elements is formed by etching. CONSTITUTION:A part to be formed with a separating groove of an element 1 of a semiconductor substrate 2 is covered with an insulating film 9 not to be epitaxially grown of an oxide film to be formed, for example, by an ordinary pressure CVD method, and then a laser diode element 1 is formed of an epitaxially grown layer on the other part, for example, by a metal organic VPE method. Thus, an element separating groove 5 is resultantly formed on the film 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a separation groove for separating a semiconductor laser diode manufactured in a wafer state into each element.

[0002]

2. Description of the Related Art A semiconductor laser diode emits coherent light by passing a current through an element layer formed of a PN junction epitaxially grown on a semiconductor substrate. After the elements 1 are formed on the semiconductor substrate 2 in a grid-like alignment state as shown in FIG. 2, the inspection for determining good or bad for each element is performed by connecting the rows of the elements 1 as shown in FIG. The bar is cut out and the probe 3 is individually applied to the electrode 3 of each element 1 to check the light emission from the side surface. At this time, if a current flows through the adjacent elements 1, individual inspection cannot be performed. Therefore, the groove 5 for separating each element 1 is formed by etching.

The conventional formation of the separation groove 5 is performed by the etching method described in FIG.

First, as shown in FIG. 4 (a), an element layer 6 is formed on a wafer-shaped semiconductor substrate 2 by an epitaxial growth method, and then a photoresist layer (hereinafter A PR layer) 7 is formed. Next, FIG.
As shown in (b), the isolation groove 5 is formed by etching the portion without the PR layer 7. After that, after removing the PR layer 7, the entire surface of an oxide film as a protective film is deposited, a window is opened to the electrode formation portion of this oxide film, the entire surface of a metal film for electrode formation is deposited,
After forming the PR layer covering the portion of the metal film to be the electrode and removing the unnecessary portion of the metal film by dry etching,
The process in the wafer state is completed.

[0005]

In order to surely separate the elements 1 by the selective etching described above, it is necessary to perform the etching for a considerably long time, and therefore, the etching is performed more than necessary. .. In addition, various types of etching solutions having different compositions are used, and the etching rates are different, so that the shape of the separation groove 5 becomes unstable, and an etching solution having a high rate causes excessive etching. It may end up.

As described above, when etching is performed more than necessary, the side surface of the remaining element portion is, as shown in FIG.
The eave-shaped step 8 is easily formed. If there is this step 8, the portion shadowed by the step will not be exposed in the photolithography process performed to form the electrode 3 shown in FIG.
May be left whiskers. These photoresists and metal films are peeled off after the devices are individually packaged, which causes a problem of generating dust that causes characteristic defects.

When the eave-shaped step 8 is formed,
As shown in FIG. 5, when a row of elements 1 is cut out from a wafer-shaped semiconductor substrate 2, cracks may occur at the cut-out end face from which laser light is emitted, which may cause characteristic deterioration.

Therefore, the present invention solves the above problem by providing a method for forming an isolation groove of an element without performing etching that causes a step.

[0009]

According to the method of isolating a semiconductor laser diode of the present invention, an insulating film which is not epitaxially grown is previously formed on a portion of a wafer-shaped semiconductor substrate where an isolation groove is to be formed, and then another A laser diode element is formed by epitaxial growth on the portion.

In order to carry out selective epitaxial growth as described above, an oxide film formed by, for example, an atmospheric pressure CVD method is used as the insulating film, and an organic metal CVD method is used as the epitaxial growth layer.

[0011]

As described above, when the insulating film is formed in the portion where the isolation groove is to be formed in the element, there is no epitaxial growth in this portion, and when each element is formed by the epitaxial growth, the element isolation results. A groove will be formed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A manufacturing process of a semiconductor laser diode according to the present invention will be described with reference to FIG. First, as shown in FIG. 1A, an insulating film 9 is formed on a portion of a wafer-shaped semiconductor substrate 2 where a separation groove is to be formed. This is, for example, the insulating film 9
In a oxide film (S _i O ₂₎ of a predetermined thickness, normal pressure CVD
The entire surface is formed by the (chemical vapor deposition) method, the PR layer is deposited on the entire surface, a window is opened in the portion of the PR layer where the separation groove is to be formed, and an oxide film is selected using an etching solution. By etching, and then the PR film is removed with a solvent.

Next, as shown in FIG. 1A, with respect to the semiconductor substrate 2 in which the insulating film 9 is formed in the separation groove forming portion,
Element 1 consisting of PN junction by epitaxial growth method
To form. In this epitaxial growth process, the insulating layer 9
In order to prevent the epitaxial layer from growing on top of it, for example, metalorganic vapor phase epitaxy (MO-VPE) is performed with a predetermined pressure, temperature and growth rate. Here, the organic metal added to the vapor growth gas is, for example, TMG (trimethylgallium) or TEG (triethylgallium).
Etc. are used.

The element 1 thus formed is shown in FIG.
As shown in (b), the insulating film 9 is partitioned by the isolation trench 5 formed as a result of no epitaxial growth.

After that, an oxide film as a protective film is formed on the entire surface, and a window is opened to the electrode forming portion of the oxide film by the photolithography method, the entire surface of the electrode forming metal film is deposited, and the metal is formed by dry etching. The electrode 3 is formed on the element 1 as shown in FIG. 3 by a process such as removal of an unnecessary portion of the film, and the final process in the wafer state for manufacturing the semiconductor laser diode is completed.

At this time, since the side surface of each element 1 has a natural inclination of epitaxial growth and no eaves or the like due to a step is formed, there is no shaded portion in the exposure step or the dry etching step, and when the electrode layer is formed. In the PR process, the photoresist and the metal film are not left. Therefore, the remaining photoresist or metal film is not peeled off after packaging of the semiconductor laser diode and becomes dust, which does not cause deterioration of characteristics.

As shown in FIG. 5, the semiconductor substrate 2 on which the element 1 of the semiconductor laser diode is formed is
The elements 1 in a row are cut out in a bar shape so as to be continuous, and the inspection 4 is applied to each element 1 for inspection. Even at the time of this cutting, since no step is formed on the side surface of each element 1, there is no phenomenon of cracking from the step, the yield is improved, and the characteristic deterioration due to the crack is eliminated.

[0018]

According to the present invention, an element of a semiconductor laser diode is formed by an epitaxial growth method in a portion excluding an insulating film which is not epitaxially grown, so that an isolation groove necessary for individual inspection of the element can be formed without a step. It can be made in various shapes. Therefore, the residual phenomenon of the photoresist and the metal film in the electrode formation process performed after this is eliminated to improve the reliability of the product, and the crack due to the step at the time of cutting into the bar state for the inspection before the element isolation. It is possible to improve the retention by eliminating the occurrence of.

[Brief description of drawings]

FIG. 1 is a cross-sectional perspective view showing a manufacturing process of a semiconductor laser diode according to the present invention.

FIG. 2 is a plan view showing a semiconductor laser diode in a wafer state.

FIG. 3 is a perspective view showing a semiconductor laser diode cut out in a bar shape in a connected state from a wafer for inspection.

FIG. 4 is a sectional view showing a method for forming an element isolation groove of a semiconductor laser diode by a conventional method.

5 is a partial perspective view of a semiconductor wafer showing a cross section of how an eave-shaped step is formed when a separation groove is formed by the method shown in FIG.

[Explanation of symbols]

 1 Semiconductor laser diode element 2 Semiconductor substrate 3 Electrode 4 Meter reading 5 Element separation groove 9 Insulating film

Claims (3)

[Claims] 1. A laser diode element is formed by previously depositing an insulating film which is not epitaxially grown on a portion of a wafer-shaped semiconductor substrate where an element isolation groove is to be formed, and epitaxially growing the portion other than the portion where the insulating film is formed. And a method for separating a semiconductor laser diode. 2. The element isolation method for a semiconductor laser diode according to claim 1, wherein the insulating film is formed by an atmospheric pressure CVD method. 3. The epitaxial growth layer is formed of organometallic VPE.
The method for isolating a semiconductor laser diode according to claim 1, wherein the element is separated by a method.